Its name stems from antiquity, in Latin it was known as Timacus and in Ancient Greek Timachos", Τίμαχος.

The Timok turns north-west after its formation at Zaječar, running next to the villages of Vražogrnac, Trnavac, Čokonjar, and Brusnik.

In the lower course the Timok has no major settlements on the Serbian side (though flowing only 7 km from Negotin).

The average discharge is 24 m3/s, but it can grow to 40 m3/s, and the Timok is part of the Black Sea drainage basin.

The river has been greatly ecologically damaged in recent years by the mining and heavy metal industry in Bor and Krivelj and is consequently polluting the Danube with lead, copper and cadmium.